I have just got a hot plate ("plata") and I want to use it with a timer. If foods are left on the hot plate when the timer is off (and the hot-plate is cold), can they be reheated when the plate is turned on by the timer? What about liquids? Thank you

ב"ה Shalom, This question has already been asked in the Hebrew counterpart to this website, so I will reiterate what has been written which is basically based on Shemirat Shabbat Kehilchata (Vol. I, chap 1:32 and footnotes 85, 126) with some additional comments and notes. On one hand, Rav Moshe Feinstein zt"l , (Igrot Moshe 4:60) restricted the use of a timer for Shabbat for the use of lights only, however it has already become a common thing to use it for heating food on Shabbat as well. The timer may be used to warm food on Shabbat which is fully cooked and solid food. If the food was placed on the hotplate before Shabbat, the pot can be placed directly on the hotplate. However, if you plan to place food on the hotplate on Shabbat, even when the hotplate is off, it should be placed on top of something which leaves space between the hotplate and the pot. However, if the food is not fully cooked or there are liquids, it may not be warmed on Shabbat by the timer. All the best